The GP's guide to Parkinson's

The GP’s guide to Parkinson’s

Diagnosis

A definite diagnosis of Parkinson’s is difficult. It is important that there is an early diagnosis. If the condition is suspected, a patient should quickly be referred – untreated – to a neurologist or a geriatrician with a special interest in Parkinson’s. There may be a local ‘movement disorder clinic’. The NICE Guideline Parkinson’s: diagnosis and management in primary and secondary care says referral time should be no more than 6 weeks and should not exceed 2 weeks in cases where the condition is severe or complex

Signs and symptoms suggestive of Parkinson’s are:

bradykinesia (slow movements)

tremor

hypokinesia (poverty of movement)

rigidity

The condition is diagnosed following a detailed clinical examination. The specialist should use the Parkinson’s UK Brain Bank Criteria. There are no laboratory tests or easily available imaging tests to help make the diagnosis

While a DaTSCAN may assist in making the diagnosis, this is only available in some centres. It is more likely to be used to exclude other conditions that may have similar symptoms

Patients with Parkinson’s should be reviewed regularly and the diagnosis reconsidered if atypical features appear. The rate of onset is extremely variable

There are some conditions that have symptoms similar to Parkinson’s and are referred to as ‘parkinsonism’:

Neuroleptic drugs, including anti-emetics, can induce symptoms of parkinsonism

Follow-up

Ideally, patients with Parkinson’s should receive a follow-up by a Parkinson’s specialist every 6–12 months to optimise the treatment and reassess the diagnosis

As the illness evolves, it is not unusual for the diagnosis to change

If the GP has a special interest in Parkinson’s then the patient can be followed by using a local shared care protocol

If there is a Parkinson’s Nurse Specialist (PDNS), they can co-ordinate optimal care with the patient, carer, GP, and specialist. The PDNS revolutionises care by bringing it into the community and the patient’s home. All patients with Parkinson’s should have access to a PDNS

Maintaining independence is a high priority, along with home safety

Occupational therapy and physiotherapy follow-up will facilitate independence. Speech therapy will help to preserve speech and swallowing

The GP can co-ordinate care by using a computerised register to ensure patients are not referred on and then forgotten about

Medication is usually provided by the GP, who is well placed, with the PDNS, to monitor compliance issues related to repeat prescribing

A medication review will ensure that no other medication is exacerbating the condition

Do not stop medication abruptly as it can cause neuroleptic malignant syndrome, which can be dangerous

Motor symptoms

Patients with Parkinson’s become slower in all movements (bradykinesia) and gradually the characteristic parkinsonian rigidity takes possession of the limb, usually on one side – both sides will be affected as the condition progresses. On the affected side, the arm stops swinging when walking and the leg feels heavy

Hypokinesia (poverty of movement) manifests as loss of facial expression, loss of arm swing, and difficulty with movement

In the majority of patients, but not all, the tremor appears not when the limb is in motion but when at rest, or perhaps when carrying out a task such as holding up a newspaper. It is a fine, rhythmic movement – about two to five per second – and may appear in the thumb and index finger (‘pill-rolling’) or at the wrist. The leg also, when inadequately supported, will shake in the same way

The tremor is aggravated by fatigue, emotional stress, or the knowledge that the tremor is being looked at. It usually only affects one side of the body initially

Clinical examination should, as usual, begin with the observation of the patient as he/she approaches the examiner:

the face, the stance, and gait are all good indicators of Parkinson’s

the arms and legs are not paralysed

the muscle tone is increased with the classic ‘lead pipe’ or ‘cog-wheel’ rigidity. Movements tend to be slow and restricted in range

the tendon reflexes are normal or even a little brisk and the planter reflexes are flexor. If reflexes are brisk, this raises the possibility of atypical parkinsonism

Imperceptibly, the natural mobility of the patient’s face fades and this becomes a little set and, later, a ‘masked’ appearance develops. Although the voice tends to lose its natural inflexions and eventually becomes very weak

Although the lack of facial expression can give the wrong impression about the mental state, many patients have unrecognised depression

Non-motor symptoms

Early recognition of non-motor symptoms (NMS) is essential. The GP or PDNS can assess and monitor these continuously, providing specific advice and support for the person and their family, as well as ensuring referral on to the multidisciplinary team

A questionnaire for people with Parkinson’s to complete to help health professionals assess their non-motor Parkinson’s symptoms is available to download from parkinsons.org.uk

Neuropsychiatric symptoms include:

anxiety

apathy

depression

psychosis and visual hallucinations

dementia

sleep disturbances

restless legs syndrome (RLS)

rapid eye movement (REM) sleep behaviour disorder (RBD)

hypersomnolence

Autonomic disturbance (dysautonomia) symptoms include:

urinary dysfunction

constipation

sexual dysfunction

orthostatic (postural) hypotension

weight loss

dysphagia

excessive sweating (hyperhidrosis)

excessive saliva (sialorrhoea)

Sensory disturbances include:

pain

olfactory dysfunction

Treatment

Unless the GP has a special interest in the condition, treatment is best initiated by a Parkinson’s specialist in liaison with the PDNS, using a local shared care protocol that the GP can refer to. The GP can then prescribe Parkinson’s medication but only if a robust local shared guideline is available. Ideally the monitoring will be carried out by a PDNS

Communication by phone between GP, PDNS, and Parkinson’s specialist will often smooth out any issues regarding responsibility and reluctance to prescribe drugs that a GP has no experience of prescribing

Your patient should have access to physiotherapy, occupational therapy, and speech and language therapy

Levodopa

Levodopa (L-dopa) is a dopamine precursor that is converted to endogenous dopamine within the brain by the enzyme dopa decarboxylase

L-dopa can be combined with either:

benserazide (co-beneldopa), which inhibits the actions of extracerebral dopa decarboxlase

carbidopa (co-careldopa)

also available as an intestinal gel, which is administered directly and continuously to the upper part of the small intestine, via a permanent intestinal tube. This ensures that the drug is absorbed into the blood at a constant rate

carbidopa and entacapone

These drugs remain the mainstay of therapy and it is important to titrate the dosage to the patient’s requirement

The problem with L-dopa is that, in the longer term, the timing of each dose becomes critical, as there is frequently loss of effect before the next dose is administered

In time, the majority of patients on this drug will experience these adverse effects

Manipulation of the dosage, time of administration, and type of preparation will help. In addition, attention should be paid to diet, as a high-protein diet can interfere with the absorption of L-dopa from the gastrointestinal tract, and some patients benefit from taking their medication about 45 minutes before meals

Dopamine agonists

An alternative strategy is to use drugs that have a dopamine-like action. The dopamine agonists stimulate dopamine receptors and can be used either alone or in conjunction with L-dopa

They produce fewer long-term side-effectsbut they are much more likely to cause hallucinations in older patients. In addition, they have to be introduced very gradually, as they do cause nausea, sickness, ankle swelling, and dizziness related to low blood pressure. They have to be used with care but are very useful

While some dopamine agonists can have a side-effect of heart valve fibrosis and reddening of the legs, others, including pramipexole, ropinirole and apomorphine, do not

Studies have also shown that a small, yet significant, percentage of people with Parkinson’s who have been prescribed certain dopamine agonists will experience impulsive and compulsive behaviour, which affects around 17% of people on dopamine agonists, but also affects 7% of people on levodopa:

patients and carers should be asked if there have been any changes to the patient’s behaviour as they may not recognise the changes or be willing to acknowledge the problem. Examples include spending more, including gambling, aggressive outbursts, an increase in risk-taking behaviour, an increase in sexual desire or developing other obsessive behaviours

this can have a seriously detrimental effect on the lives of the person directly affected, as well as their families. Studies have highlighted that drug reduction or withdrawal can, in many cases, reduce excessive behaviours

Rotigotine is delivered once daily by skin patch. Although it has not yet been officially approved by NICE it is in clinical use

Apomorphine can only be administered subcutaneously and is helpful in patients who have severe fluctuations in their symptoms. With appropriate training, it can be self-administered and there is now a preparation for continuous

subcutaneous infusion with a syringe driver

Dopamine agonist withdrawal syndrome

Dopamine agonist withdrawal syndrome occurs when a person’s dopamine agonist treatment is stopped or reduced. People who experience impulsive or compulsive behaviour as a side effect of dopamine agonists are most at risk of developing dopamine agonist withdrawal syndrome

COMT inhibitors work by blocking an enzyme called catechol-O-methyl transferase (COMT), which breaks down L-dopa

as a result they slow the destruction of L-dopa in the body

COMT inhibitors are, therefore, prescribed for use with L-dopa to prolong the duration of action

Anticholinergics (e.g. trihexyphenidyl):

these were the first drugs to become available for the treatment of Parkinson’s

while they tend to help the tremor, they are no longer recommended due to high risk of side-effects, especially in the elderly, and concerns about their effect on cognitive function

Antidepressants:

as depression is present in up to 45% of people with Parkinson’s, these are often important in the management of the condition

there are no specific rules for their use and GPs should use drugs they are familiar with

selective serotonin-reuptake inhibitors, e.g. citalopram, are possibly the most useful but there is a rare adverse interaction with selegiline and rasagiline (hypertension and CNS excitation)

Anti-emetic drug of choice is domperidone

Drugs that are best avoided in Parkinson’s:

prochlorperazine

metoclopramide

perphenazine

flupentixol

chlorpromazine

fluphenzine

haloperidol

pimozide

sulpiride

trifluoperazine

Withdrawal of therapy

If any of the drugs used for treating Parkinson’s need to be stopped, it is important this is done gradually. Abrupt withdrawal of certain drugs can result, albeit rarely, in neuroleptic malignant syndrome. This is a very serious condition that may cause death from complications of the respiratory, cardiovascular or renal system